Positive electrode active material precursor for lithium-ion secondary battery and method for producing positive electrode active material precursor for lithium-ion secondary battery

Abstract

A positive electrode active material precursor for a lithium-ion secondary battery, containing a metal composite hydroxide, wherein the metal composite hydroxide is in a form of a particle having a core-shell structure whose surface is coated with an iron compound, the core-shell structure is constituted by a core portion and a shell portion, the core portion contains nickel and aluminum as metal elements, the shell portion contains iron as a metal element, when a composition of the core portion is represented by Ni (1-x) Al x (OH) 2 , 0.01≤x≤0.2 is satisfied, and a molar ratio (M 2 /M 1 ) between a molar amount M 1 of the metal element in the core portion and a molar amount M 2 of the metal element in the shell portion satisfies M 2 / M 1 = 1 / 100 ⁢ to ⁢ 1 / 5.

What is claimed is: 
     
         1 . A positive electrode active material precursor for a lithium-ion secondary battery, comprising a metal composite hydroxide, wherein
 the metal composite hydroxide is in a form of a particle having a core-shell structure whose surface is coated with an iron compound,   the core-shell structure is constituted by a core portion and a shell portion,   the core portion contains nickel and aluminum as metal elements,   the shell portion contains iron as a metal element,   when a composition of the core portion is represented by Ni (1-x) Al x (OH) 2 ,   0.01≤x≤0.2 is satisfied,   and   a molar ratio (M 2 /M 1 ) between a molar amount M 1  of the metal element in the core portion and a molar amount M 2  of the metal element in the shell portion satisfies   
       
         
           
             
               
                 
                   M 
                   2 
                 
                 / 
                 
                   M 
                   1 
                 
               
               = 
               
                 
                   1 
                   / 
                   100 
                 
                 ⁢ 
                     
                 to 
                 ⁢ 
                     
                 
                   1 
                   / 
                   5. 
                 
               
             
           
         
       
     
     
         2 . The positive electrode active material precursor for a lithium-ion secondary battery according to  claim 1 , wherein the core portion does not include the same crystal structure as that of an α-type nickel hydroxide. 
     
     
         3 . The positive electrode active material precursor for a lithium-ion secondary battery according to  claim 1 , wherein the shell portion contains one or more iron compounds selected from iron (II) hydroxide, iron (III) hydroxide, iron oxyhydroxide, and triiron tetraoxide. 
     
     
         4 . The positive electrode active material precursor for a lithium-ion secondary battery according to  claim 1 , having an average particle size of 1 to 25 μm and a tap density of 1.30 g/mL or more. 
     
     
         5 . The positive electrode active material precursor for a lithium-ion secondary battery according to  claim 1 , having a specific surface area of 2 to 50 m 2 /g. 
     
     
         6 . A method for producing the positive electrode active material precursor for a lithium-ion secondary battery according to  claim 1 , the method comprising
 a step of coating a hydroxide containing nickel and aluminum with an iron compound under an inert gas atmosphere.